The Dragon-helm was crafted for a Dwarf and was too large and heavy for an Elf. Even Men found the helm was too massive, and only Hador had the strength to wear it. It passed through Hador's descendants until Túrin Turambar finally bore it to battle.
Túrin was monstrous in war and took one of his many titles from it: Gorthol, the "Dread Helm". The last clear record of the Dragon-helm is at the Battle of Tumhalad, where Túrin is known to have worn it. Beyond this, he may have taken it with him to the Forest of Brethil, and perhaps even wore it at the slaying of Glaurung himself. After Túrin's death the great heirloom of the House of Hador was lost to history.

"That helm was made of grey steel adorned with gold, and on it were graven runes of victory. A power was in it that guarded any who wore it from wound or death, for the sword that hewed it was broken, and the dart that smote it sprang aside.
It had a visor (after the manner of those that the Dwarves used in their forges for the shielding of their eyes), and the face of one that wore it struck fear into the hearts of all beholders, but was itself guarded from dart and fire. Upon its crest was set in defiance a gilded image of the head of Glaurung the dragon; for it had been made soon after he first issued from the gates of Morgoth."

Later History

While it is uncertain what ultimately became of the Dragon-helm, Tolkien presented several versions. One, noted in the Wanderings of Húrin says that Húrin was returned the Dragon-helm during his time in Brethil but as with many subjects in Tolkien's earlier age the truth will never be known